Exhaust & silencer

How it works

The exhaust carries burnt gases away from the engine, reduces noise and, on modern bikes, cleans emissions with the catalytic converter. It is made up of the header (bolted to the cylinder head), sometimes a collector box, the catalytic converter and the silencer. It is mounted to the frame with brackets and rubber bushes. The gasket between header and head runs very hot: if it leaks, you hear a ticking or puffing at idle and black marks appear. With heat, condensation and time, the silencer can rust through or its packing break down: the sound gets louder and deeper. An exhaust that is too loud or not type-approved can be fined, and removing the catalytic converter causes problems with noise and inspections. A blocked system (clogged catalyst, obstructed baffle) strangles the engine. A broken bracket makes the pipe knock against the frame.

Maintenance tips

• ✓Listen at idle on a cold engine: a ticking near the head can mean a leaking header gasket.
• ✓Replace the header gasket every time the exhaust is removed.
• ✓Check the brackets and rubber bushes: a pipe that vibrates or touches the frame must be re-secured.
• ✓Keep a type-approved exhaust, with its catalytic converter and markings, to stay legal.
• ✓Don't touch the exhaust after riding: it stays very hot for a long time.